Trius, Optimer, bought for up to $1.62 billion

San Diego  Two biotech companies with San Diego operations were purchased Tuesday for up to $1.62 billion by Cubist Pharmaceuticals, which said the companies provide important antibiotics that will bolster its acute hospital care business.

San Diego-based Trius Therapeutics, developer of the antibiotic tedizolid, will be sold to Lexington, Mass.-based Cubist for about $707 million cash, or $13.50 per share.

Trius shares closed at $11.71 Tuesday before the announcement. Trius shareholders also get contingent rights depending on sales, bringing the value of the deal to as much as $818 million.

Cubist is also buying Optimer Pharmaceuticals, which moved to New Jersey from San Diego last year, for about $535 million cash. or $10.75 per share.

Optimer shares closed at $13.29 Tuesday before the announcement. Optimer, which maintains some operations in San Diego, could bring up to $801 million, or $15 per share, if sales targets are met for its antibiotic, Dificid.

Optimer said in February that it was considering “strategic alternatives,” which is often an indication a sale is being pursued.

The purchases are expected to be completed by the end of the year.

Both Dificid, already on the market, and tedizolid, which has completed Phase 3 clinical trials, treat extremely dangerous “superbugs” that resist conventional antibiotics. Pharmaceutical companies have lagged in developing antibiotics over the last few decades. Meanwhile, microbes have evolved growing resistance to them.

Tedizolid treats methicillin-resistant Staphylococcus aureus, or MRSA and other serious gram-positive bacterial infections. Cubist’s top-selling drug is Cubicin, also used to combat MRSA. Cubicin had sales of $859.7 million in 2012, generating about 93 percent of the company’s revenue.

Dificid, already on the market, treats infections caused by the bacterium C. difficile. Cubist is co-promoting Dificid with Optimer under an agreement that began in April 2011.

“The stars were aligned,” to allow the simultaneous purchases, Mike Bonney, Cubist’s chief executive, said in a conference call Tuesday.

It’s unclear how many Trius and Optimer employees will remain with Cubist, or whether Cubist will maintain the companies’ San Diego operations. Cubist did not directly a question about their future. However, it hinted that at least some of the employees would continue with the company.

“Trius and Optimer are prime examples of the high caliber innovation in San Diego we have known and respected for many years,” Bonney said in a statement. “We have the highest regard for the talented employees at both companies. We look forward to meeting with them, listening to them, and working with them to improve the lives of patients with difficult-to-treat infections.”

Trius had about 100 employees as of March. Optimer employed 281 companywide as of Feb. 15, according to a regulatory filing. Optimer has not said how many employees remain in San Diego.

The top three shareholders in Trius as of April 5 were InterWest Partners IX, with 7.41 percent ownership; Versant Ventures III, with 6.76 percent; and Kleiner Perkins Caufield & Byers, with 6.57 percent.

Optimer’s top three shareholders as of March 31 were FMR, with 12.37 percent of shares outstanding; T. Rowe Price, with 10.89 percent; and Wellington Management Co., with 8.38 percent.

In March, Trius said it planned to file for marketing approval for tedizolid, based on strong Phase 3 clinical trial results. Tedizolid was found to be as effective as Zyvox, an antibiotic from Pfizer already on the market, even when given less frequently. In a placebo-controlled trial, Zyvox was given twice a day for 10 days and tedizolid once daily for six days. They were compared on the decrease in the lesion area.

Because of the need for more effective antibiotics, drugs like tedizolid are given preferential treatment by the U.S. Food and Drug Administration. In January, the FDA granted Trius a faster review schedule and incentives to bring tedizolid to market.